Loading-Induced Earth's Stress Change Over Time

Abstract

We establish a physical framework and build a preliminary database of stress changes on the Earth from 2000 to 2017 in a global scale and at various depths. We consider six loading forces that would generate stress changes on the Earth: hydrological loading, atmospheric pressure, ocean water (including tides and nontidal variation), solid lunisolar tides, pole tide, and postglacial rebound (PGR). The maximum amplitudes of normal deviatoric stress changes on the Earth's surface caused by hydrological loading, atmospheric pressure, and solid lunisolar tides reach 10−2 bar, those by pole tide 10−4–10−3 bar, and those by ocean tides 10−1 bar mostly in the coastal regions. The shear stress changes are about 1 order of magnitude smaller than the normal deviatoric stresses. The PGR-induced stress rates are 10−3–10−2 bar/year. Stress variations caused by the different forces also exhibit different spatial patterns, with large hydro-induced stresses mainly distributed in torrid and frigid zones, atmosphere-induced stresses in temperate and frigid zones, and ocean-induced stresses in coastlands and PGR-induced stress rates in Greenland, north Europe, North America, and Antarctica. The hydro-induced stresses exhibit significant seasonal variations in Amazon Basin, northern India, and central Africa and persistent increase/decrease in Antarctica, Greenland, and Alaska due to ice shelf melting. All loading-induced stress changes exhibit significant depth variations. The stress database would provide a resource for better understanding the triggering mechanisms of various tectonic events, and the physical framework we establish to build the database could be useful for better studying properties and physical states of Earth's interior.